Document shredders are used to destroy documents (that is to say files) containing confidential information. Documents of this kind are primarily to be understood to be sheets (of paper) but also folders, floppy disks, CDs or other data storage media.
In order to destroy, that is to say shred, the documents, a document shredder has a motor-operated cutting unit which cuts the document, which is to be shredded, into pieces. To this end, the document shredder has a document intake and a container which receives the documents which have been cut into pieces.
One problem with document shredders is that they can be overloaded by documents which are too thick, in particular by too many sheets, being inserted. In order to pre-empt overloading, which is harmful to the document shredder, and to prevent paper becoming jammed or stuck, customary document shredders automatically switch off at a predetermined load limit value, that is to say they switch off the drive of their cutting unit, and possibly initiate a reverse mode by way of which the drive direction of the motor is reversed and by way of which the document which is to be shredded is discharged again.
The prior art also discloses equipping document shredders with a turbo mode in which the torque of the motor which drives the cutting unit is increased.
DE 195 25 027 A1 describes, for example, a document shredder of which the cutting unit is driven by a drive motor which is in the form of a capacitor motor with an operating capacitor. When the drive motor of the cutting unit is overloaded, said drive motor is operated for a short time in the reverse mode and switched off. An auxiliary capacitor which can be connected in parallel to the operating capacitor of the drive motor is then switched on for a short period, preferably for passage of documents, as a result of which the torque of the drive motor can be increased.
One disadvantage of said document shredder is that activation of the turbo mode, that is to say the increase in the torque, necessarily requires that an additional electrical component of the electric motor is connected. Therefore, firstly, it is necessary for this additional component to be present and functional. Secondly, the turbo mode cannot be activated simply by adjusting or setting the operating parameters of the motor. Therefore, the solution is a hardware-based solution with which purely software-based activation is impossible. A further disadvantage is that a capacitor motor, as is known, has a low torque at low rotation speeds, and therefore the increase in the torque by the auxiliary capacitor primarily constitutes compensation of this drop in torque.